It is conventional practice to form a low-reflection coating on a glass sheet for the purpose of improving the function of the glass sheet, such as increasing the amount of light to be transmitted through the glass sheet or enabling prevention of glare. A low-reflection coated glass sheet including a glass sheet and a low-reflection coating formed on the glass sheet is used, for example, in a photoelectric conversion device such as a thin-film solar cell. In this case, placing the low-reflection coating on the sunlight-incident side of the low-reflection coated glass sheet allows more sunlight to be introduced to the photoelectric conversion layer or solar cell element of the photoelectric conversion device. This can result in an increase in the electricity generated by the photoelectric conversion device.
For example, Patent Literature 1 describes a cover glass for photoelectric conversion devices that has a reflection-reducing film. This cover glass having the reflection-reducing film is produced by applying a coating liquid containing fine silica particles and a compound as a binder source to a glass sheet having certain surface asperities by spraying, followed by drying and sintering. The average light transmittance of this cover glass in the wavelength range of 380 nm to 1100 nm can be increased by 2.37% or more, compared to that of a glass sheet having no reflection-reducing film.
Patent Literature 2 describes a glass substrate including a glass sheet and a porous anti-reflection layer formed on the glass sheet. This glass substrate is produced by depositing a blend for priming on one surface of an ultra-transparent glass sheet by dip coating, then drying the blend on the glass sheet to obtain a substrate, then depositing another mixture on the substrate by dip coating, and finally subjecting the substrate to a predetermined heat treatment. The blend for priming is prepared by adding tetraethoxysilane (TEOS) and zirconium acetylacetonate to a predetermined solution. The other mixture is prepared by adding tetraethoxysilane (TEOS), aluminum acetylacetonate, and colloidal silica to a predetermined solution. This glass substrate has been observed to exhibit an increase of 2.2% to 2.6% in light transmittance in the wavelength range of 300 nm to 1100 nm.
Patent Literature 3 describes a coating composition prepared by using a PGME-dispersed silica sol and a binder solution. The PGME-dispersed silica sol is one prepared by adding propylene glycol monomethyl ether (PGME) to a dispersion of silica, and the binder solution is one prepared by mixing tetraethoxysilane and aluminum nitrate nonahydrate. An aqueous dispersion of colloidal silica having a dispersed particle diameter greater than an average primary particle diameter is used in the PGME-dispersed silica sol. A coating obtained by using this coating composition has a refractive index of 1.2656 to 1.2960 at a wavelength of 633 nm.